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Spring Boot Admin server

To enable remote management for Spring Boot applications on Kubernetes, follow below steps:

  1. Add below maven dependencies to your Spring Boot Admin server application, see pom.xml:

    <dependency>
  <groupId>de.codecentric</groupId>
  <artifactId>spring-boot-admin-starter-server</artifactId>
  <version>${spring-admin-server.version}</version>
</dependency>

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-kubernetes-all</artifactId>
</dependency>

  2. Add @EnableAdminServer, @EnableDiscoveryClient and @EnableScheduling annotations to your main Spring Boot Admin Server application class:

    /**
 * SpringBootAdminServer
 *
 * @author Manuel Núñez Sánchez (manuel.nunez@hawkore.com)
 */
@SpringBootApplication
@EnableAdminServer
@EnableDiscoveryClient
@EnableScheduling
public class SpringBootAdminServer {

    /**
     * The entry point of application.
     *
     * @param args
     *     the input arguments
     */
    public static void main(String[] args) {
        SpringApplication app = new SpringApplication(SpringBootAdminServer.class);
        app.setBannerMode(Mode.OFF);
        app.run(args);
    }

}

  3. Create a Kubernetes ConfigMap for Spring Boot Admin Server to tell how to find Spring Boot applications to manage:

    IMPORTANT: In our case, the name of this ConfigMap must be equals to sb-admin-server, as defined in application.properties spring.application.name property.

    # Config Map for Spring Boot Admin Server to auto-discover Spring Boot applications to manage
apiVersion: v1
kind: ConfigMap
metadata:
  name: sb-admin-server
  namespace: my-mule4-stack
data:
  application.yml: |-
    spring:
     cloud:
      kubernetes:
        discovery:
          all-namespaces: true
          service-labels:
            spring-boot-managed: true

  4. Kubernetes services grouping Spring Boot applications to manage must include label spring-boot-managed: "true", for example:

    # Service (Load balancer) for Quiz REST Api: api endpoints, RAML console and Spring Boot management (actuator)
apiVersion: v1
kind: Service
metadata:
  name: mule-api-app-service
  namespace: my-mule4-stack
  labels:
    app: mule-api-app
    spring-boot-managed: "true"
spec:
  ports:
    - name: "mule-http"
      port: 8081
      targetPort: 8081
    - name: "management"
      port: 8888
      protocol: TCP
  selector:
    app: mule-api-app

Spring Boot Admin in Cluster - ignite Configuration for Kubernetes

Clustering Spring Boot Admin Server instances requires to provide a mechanism to share information about Spring Boot application instances across Spring Boot Admin Server nodes, so, as we want to work with GridGain we have implemented a NotificationTrigger to deduplicate notifications in cluster and an EventeStore backed by a distributed GridGain cache, see org.hawkore.springframework.boot.admin.cluster.IgniteNotificationTrigger and org.hawkore.springframework.boot.admin.cluster.IgniteEventStore implementations for more details:

@Bean
public IgniteEventStore eventStore(@Autowired Ignite ignite,
    @Value("${spring.boot.admin.server.max_events_per_aggregate:100}") int maxLogSizePerAggregate) {
    CacheConfiguration<String, List<InstanceEvent>> config = new CacheConfiguration<>();
    config.setName(nameEventStore);
    config.setAtomicityMode(CacheAtomicityMode.TRANSACTIONAL);
    config.setCacheMode(CacheMode.REPLICATED);
    return new IgniteEventStore(maxLogSizePerAggregate, ignite.getOrCreateCache(config));
}

@Bean(initMethod = "start", destroyMethod = "stop")
@ConditionalOnMissingBean(NotificationTrigger.class)
public NotificationTrigger notificationTrigger(@Autowired Ignite ignite,
    @Autowired Notifier notifier,
    @Autowired Publisher<InstanceEvent> events) {
    CacheConfiguration<String, Long> config = new CacheConfiguration<>();
    config.setName(nameNotificationStore);
    config.setAtomicityMode(CacheAtomicityMode.TRANSACTIONAL);
    config.setCacheMode(CacheMode.REPLICATED);
    // we dont want to preserve old notifications for a long time...
    // so set an expiry policy to auto remove them after a time
    config.setExpiryPolicyFactory(CreatedExpiryPolicy.factoryOf(Duration.TEN_MINUTES));
    return new IgniteNotificationTrigger(notifier, events, ignite.getOrCreateCache(config));
}

Configure IP finder on ignite-config.xml as org.apache.ignite.spi.discovery.tcp.ipfinder.kubernetes.TcpDiscoveryKubernetesIpFinder with the kubernetes service name to find other Spring Boot Admin server nodes and the namespace.

 <bean id="ignite-config" class="org.apache.ignite.configuration.IgniteConfiguration">
    ...

    <!-- Explicitly configure TCP discovery SPI -->
    <property name="discoverySpi">
      <bean class="org.apache.ignite.spi.discovery.tcp.TcpDiscoverySpi">
        <property name="ipFinder">
          <!--
          Enables Kubernetes IP finder and set namespace and service name (cluster) to find SERVER nodes.
          -->
          <bean class="org.apache.ignite.spi.discovery.tcp.ipfinder.kubernetes.TcpDiscoveryKubernetesIpFinder">
            <property name="shared" value="true" />
            <property name="namespace" value="my-mule4-stack" />
            <property name="serviceName" value="sb-admin-server-service" />
          </bean>
        </property>
      </bean>
    </property>

    ...
</bean>

Kubernetes artifacts

Build

Build docker image (docker.hawkore.com/k8s/spring-boot-admin-server-gg:latest):

mvn clean install -Pdocker